Paper Making Process Video Lecture | Chemical Technology - Chemical Engineering

sappy paper is manufactured from wood
grown and sustainably managed forests
and plantations the timber used for
paper production comes either from
deciduous trees such as birch poplar
beach and eucalyptus or conifer trees
like spruce fir and pine conifer wood
has longer fibers than deciduous species
and generally form stronger papers
when the logs arrived at the wood yard
they are fed into a rotating drum which
removes the bark the logs are then
chipped
the largest source of woodchips for
paper making is the recycled offcuts
from industrial source
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the wood chips are transported to the
pulp mill on a conveyer belt as they
enter the pulp mill the wood chips are
fed into a digester where they are
cooked in an acid solution to dissolve
the lignin and separate the plant fibres
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we call the pulp obtained from this
process wood free because the lignin has
been dissolved the fibers are washed to
remove the acid solution and the pulp is
now soft and fibrous before it can be
used to make white paper the pulp is
bleached and any residual lignin which
would cause the paper to yellow with age
is filtered out to protect the
environment this bleaching is chlorine
free using oxygen and peroxide the
yellow brown wood chips that entered the
pulp mill have now been turned into a
soft white pulp the principal raw
ingredient for making paper
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this treated pulp can be dried bailed
and transported to other paper mills
which may either not have their own pulp
mill or may require a specific type of
pulp to give the paper particular
characteristics whether produced on site
or bought on the market the pulp enters
the paper mill and is mixed with water
the pulp solution is refined by passing
it through a series of rotating and
stationary blades these give the fibers
a variable degree of clean-cut or
fibrillated ends fibrillated fibers bind
more tightly with adjacent fibers
creating stronger paper
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wood fibers alone would produce rough
textured and unevenly dense paper and
fillers such as calcium carbonate and
clay are mixed in to make the paper more
opaque and give it a more controlled
density dyes optical brighteners and
sizes may also be blended into the pulp
to improve the appearance of the paper
by far the most important process
material is water about a hundred litres
of fresh water are needed to make one
kilogram of paper sophisticated
wastewater treatment plants and closed
water circulation systems on the paper
line allow over 90% of this water to be
recycled the Pape solution is now a
carefully controlled mix of fibres
fillers and colouring agents suspended
in water ready to enter the paper
machine
the paper machine is the heart of the
paper mill
a continuously running series of
manufacturing processes that will
convert the pulp solution into the
perfect paper grade for each market
application the head box is located at
the beginning of the paper machine here
the pulp solution is injected at high
pressure directly into the space between
two continuously rotating wires these
carry the pulp into the gap former which
rapidly drains the excess water from
both sides
this immobilizes the pulp within
milliseconds of leaving the head box
turning it into a continuous web of
paper still wet and fragile but already
exhibiting its most important sheet
properties the delicate paper web is now
carried into the press section by
continuously looped wet felts which
carry away most of the water and stop
the sheet from tearing at the shoe press
the paper web is forced between a soft
rotating roller pressing against a
hydraulically actuated metal pad water
is squeezed out of the paper by this
pressure and this is absorbed and
carried away by the wet felts
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the longer section of the paper machine
contains the drying cylinders these huge
heated rollers dry the paper giving it
the strength to become self-supporting
ready for the processes which will
determine its surface qualities the
paper sheet passes along the paper
making machine at up to 1,400 meters per
minute every process is continuously
monitored to ensure its manufacturing
consistency the paper passes through a
machine calendar where 2 finely polished
steel cylinders are to precisely
determine width apart ensure that the
paper thickness is consistently even
the paper event passes through a series
of sizing and coating presses here
starch and coating colors are applied to
its surface using a film press process
the coating color is sprayed onto an
elastic roll which then transfers the
coating film to the paper web film press
coating creates a uniformly thick
coating layer which follows the surface
of the paper after each coating process
the surface is dried by infrared heating
panels and drying cylinders setting the
surface with sizing encourages printing
inks to dry on the surface of the paper
rather than be absorbed into the paper
increasing the color intensity of the
finished print and improving the surface
strength and water resistance of the
paper the paper is then wound onto a
series of steel cores which press
against a pope reel this makes sure that
the paper is wound at the right tension
onto each core
every hour the paper line creates a
jumbo reel containing 80 kilometres of
paper sheet 8.5 meters in width and
weighing 120 tonnes
the paper machine operators carefully
check every aspect of the base paper
quality its thickness opacity and
smoothness making sure these are exactly
as specified before allowing the robot
truck to carry the jumbo reel away for
further treatment and finishing
processes the final surface qualities of
each batch of paper are controlled in
the coating and finishing lines for
example the paper from this jumbo reel
may be sold with a gloss or matte finish
natural or bright white in color the
coating compounds are mixed according to
precise recipes in tanks in the coating
kitchen the main color pigment is
calcium carbonate which makes the paper
surface white but the coating solution
may also include pay and talcum powder
binders can be natural starches or
purely synthetic compounds such as latex
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to create a smoother surface up to two
more coatings per side are applied using
the blade coating process excess
solution is sprayed directly onto the
paper and is then scraped off by a steel
blade
depending on the pressure of the doctor
blade a uniform paper surface is created
as the irregularities in the paper are
smoothed out
each side is coated and dried in
sequence to create the correct
characteristics for each paper grade the
paper now has the correct base
characteristics and the optimum coating
consistency but it does not yet have a
perfect surface finish this is achieved
in the super calendar the paper passes
through up to ten rollers which each
apply pressure and temperature these
rolls have different surfaces such as
hard steel and soft rubber depending on
the type of gloss and surface treatment
required
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as it has wound back onto another steel
core for transport the paper in this
jumbo reel now has all the
characteristics needed for its end use
apart from one final detail its size the
jumbo reels are transported to a slitter
winder rotary blades cut the reel into
several narrow reels which are rewound
and sent forward to the finishing
Department
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several reels are simultaneously fed
into a schita which cuts the paper into
sheets and stacks these onto pallets
several printing processes like heatset
web offset cut star and label presses
newspaper in real form these reels
remain uncut and are moved forward on
automated conveyor belts
whether the paper has been cut into
sheets for a sheet press or remains in a
roll for a web offset press the final
destination is the same the packing
lines and warehouse each reel of paper
is wrapped in Kraft cardboard to avoid
damage in transport
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each pallet load of sheets is either
shrink wrapped or wrapped in rooms ready
for delivery to the customer
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every consignment of both sheets and
reels is labeled with a brand name a
batch number to identify its exact
manufacturing history and its
destination
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all that remains is to ship the paper
now a branded quality controlled product
with precise characteristics and
performance out to the customer